(a) Field of the Invention
This invention relates to a process for the preparation of 3-hydroxy-3-phenylbutan-2-one by reaction of 2,3-butanedione with the appropriate Grignard reagent at low temperature and in the presence of tetrahydrofuran, or mixtures of tetrahydrofuran and toluene. More particularly, this invention relates to the preparation of 3-hydroxy-3-phenyl-butan-2-one by reaction of 2,3-butanedione with a Grignard reagent such as phenylmagnesium bromide at a temperature below about 10.degree. C. in tetrahydrofuran, or mixtures of tetrahydrofuran and toluene.
(b) Prior Art
The preparation of 3-hydroxy-3-phenylbutan-2-one by reaction of 2,3-butanedione with an appropriate Grignard reagent is described in an article by Lapkin and Golovkova in Zuhr. Obshchei Khim (J. Gen. Chem.) 19, 701-6 (1949) and abstracted in Chemical Abstracts 44, 1057h (1950). The reaction of biacetyl with phenylmagnesium bromide (31.4 g) gave 30% methylphenylacetylcarbinol. The reaction conditions are not specifically described but earlier in the abstract the solvent used was diethyl ether and the reactants were heated for 10 hours. The preparation is also referred to in Beilsteins Handbook (1969) at page 458.
The use of 3-hydroxy-3-phenylbutan-2-one is described in U.S. Pat. Nos. 4,169,202 and 4,244,958 to make the compound 2-methyl-2-phenyl-3(2H)-furanone-5-carboxylic acid, known generically as acifran.